Much is due to inflation of real estate values which he has held and frankly is what he knows. He was also extremely fortunate with his television show and licensing. Those saved him from bankruptcy several times. My observation is that the many businesses he purchased or started outside of real estate have been abject failures. Even his real estate ventures have questionable results. Mainly he’s benefiting from being in Manhattan. Trump Air, all the casinos in NJ , Trump University, Trump steaks, the Washington DC hotel, golf course in Scotland etcetera. He’s shown either incompetent management or poor choice of investment time after time. His credit is so poor he has to go to Russia for loans.